ELG3336 Lab 1

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University of Ottawa *

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3336

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Electrical Engineering

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Jan 9, 2024

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ELG3336- Laboratory Report #1 TA- Matt Emma Buchanan- 300240466 Shea Gordon-McIntosh- 300244911

Page 1 Table of Contents Table of Contents 1 1 Introduction 2 2 Procedure 2 2.1 Connecting AC and DC Power Supply 2 2.2 Inverting Amplifier 3 2.3 Non Inverting Amplifier 3 3 Calculations 4 3.1 Calculated Values from Pre- Lab and Lab Experiment 4 3.2 Inverting Amplifier Images 6 3.3 Non-Inverting Amplifier Images 7 4 Discussion 8 5 Conclusion 9 6 References 10 7 Appendix 11 List of Figures Figure 1. Breadboard configuration of inverting amplifier circuit. 6 Figure 2. Oscilloscope with Input Voltage of 1V. 6 Figure 3. Oscilloscope with Input Voltage of 2V. 6 Figure 4. Oscilloscope with Input Voltage of 3V. 6 Figure 5: Breadboard configuration of non- inverting amplifier circuit. 7 Figure 6: Oscilloscope with input voltage of 1V. 7 Figure 7: Oscilloscope with input voltage of 2V. 7 Figure 8: Oscilloscope with input voltage of 3V. 7 List of Tables Table 1. Pre-Lab Inverting Amp Values 4 Table 2. Lab Inverting Amp Values 4 Table 3. Pre-Lab Non-Inverting Amp Values 5 Table 4. Lab Non-Inverting Amp Values 5

Page 2 1 Introduction Throughout this lab experiment there are two different types of amplifiers being explored. An amplifier is described as an electronic device that increases the voltage, current, or power of a signal. Operational Amplifier commonly known as Op-Amp, is a linear electronic device having three terminals, two high impedance input and one output terminal. Op-Amp can perform multiple functions when attached to different feedback combinations like resistive, capacitive or both. Generally it is used as a voltage amplifier and the output voltage of the Op-Amp is the difference between the voltages at its two input terminals. Op-Amp shows some properties that make it an ideal amplifier, its open loop gain and input impedance is infinite (i.e.,practically very high), Output impedance and offset voltage is zero (i.e.,practically very low) and bandwidth is infinite(i.e.,practically limited to frequency where its gain becomes unity). (1) Inverting Op-Amp The open loop gain(Ao) of the Op-Amp is very high which makes it very unstable, so to make it stable with a controllable gain, a feedback is applied through some external resistor(Rf) from its output to inverting input terminal(i.e.,also known as negative feedback) resulting in reduced gain(closed loop gain, Av). So the voltage at the inverting terminal is now the sum of the actual input and feedback voltages, and to separate both an input resistor(Ri) is introduced in the circuit. The non-inverting terminal of the op amp is grounded, and the inverting terminal behaves like a virtual ground as the junction of the input and feedback signal are at the same potential. (1) Non- Inverting Op-Amp In this configuration of Op-amp the input signal is directly fed to the non inverting terminal resulting in a positive gain and output voltage in phase with input as compared to inverting Op-amp where the gain is negative and output voltage is out of phase with input , and to stabilize the circuit a negative feedback is applied through a resistor(Rf) and the inverting terminal is grounded with input resistor(R2).This inverting Op-Amp like layout the at inverting terminal creates a virtual ground at the summing point make the Rf and R2 a potential divider across inverting terminal, hence determines the gain of the circuit. (1) 2 Procedure Procedure was taken from the ELG3336 Lab 1 manual. (2)

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Page 3 2.1 Connecting AC and DC Power Supply 1. Ensure that CH1 represents Channel 1 and CH2 represents Channel 2. These are separate DC power supplies designed to provide +15 Volts and -15 Volts. To achieve these voltage levels, engage the "SER" (series) button to interconnect these two channels. CH2(+) supplies +15 Volts, while CH1(-) provides -15 Volts. 2. To activate a channel, press the "ON" button. When a channel is powered on and functioning correctly, the indicator light above CH1 or CH2 will illuminate green. 3. Ensure that the waveform generator is configured to produce a sinusoidal waveform if it is not set as such by default. 4. Click on the "Parameters" option, and the frequency and amplitude settings will appear as the first and second buttons at the bottom of the interface. 5. Adjust the amplitude to match the peak-to-peak value specified in your pre-lab instructions. 6. Set the frequency to 100 Hz. 7. To activate the waveform generator, click the "Channel" button located at the top of the output socket. 8. Check the status of the channel by inspecting the indicator button on the output section. If the channel is active, the Channel button will illuminate, indicating that power is flowing through your circuit. 2.2 Inverting Amplifier 1. Configure the breadboard to match the circuit of an inverting amplifier as shown in figure 2. Assume the Rf = 15 R1, and connect DC power supply voltage (Vcc/-Vee) at ± 15 V. 3. Use RL resistor value between 1 𝑘 Ω to 4kΩ range 4. If Rf exceeds 75k Ω the op-amp will burn out in 5+ seconds 5. Set the input voltage from a Function generator ( 𝑉𝑝𝑘 − 𝑝𝑘 ) to sinusoidal at 100 Hz. 5.1. Use half the input voltage selected in the pre-lab simulation as your 𝑉𝑝𝑘 − 𝑝𝑘 5.2. If 1 volt is used set the 𝑉𝑝𝑘 − 𝑝𝑘 to 0.5 volt. 6. Click measure on oscilloscope and add peak to peak for channel 1 and channel 2. Change to channel one and add phase. 7. The phase should be around +-180 degrees on the oscilloscope reading 8. Take a screenshot or picture of your oscilloscope results with the two-channel measurement and the phase included

Page 4 2.3 Non Inverting Amplifier 1. Change the configuration of the circuit from an Inverting amplifier to a Non inverting amplifier. 2. Assume the Rf = 15 R1, and connect DC power supply voltage (Vcc/-Vee) at ± 15 V. 3. Use RL resistor value between 1 𝑘 Ω to 4kΩ range 4. If Rf exceeds 75k Ω the op-amp will burn out in 5+ seconds 5. Set the input voltage from a Function generator ( 𝑉𝑝𝑘 − 𝑝𝑘 ) to sinusoidal at 100 Hz. 5.1. Use half the input voltage selected in the pre-lab simulation as your 𝑉𝑝𝑘 − 𝑝𝑘 5.2. If 1 volt is used set the 𝑉𝑝𝑘 − 𝑝𝑘 to 0.5 volts 6. Click measure on oscilloscope and add peak to peak for channel 1 and channel 2. Change to channel one and add phase. 7. The phase should be around 0 degrees on the oscilloscope reading 8. Take a screenshot or picture of your oscilloscope results with the two-channel measurement and the phase included 3 Calculations 3.1 Calculated Values from Pre- Lab and Lab Experiment Pre-Lab Resistor Values- Rf = 30kΩ R1 = 2kΩ Lab Resistor Values- Rf = 27kΩ R1 = 2.2kΩ Table 1. Pre-Lab Inverting Amp Values Input Voltage (V) Output Voltage (V) Gain 1 -15 -15 2 -30 -15 3 -45 -15 Table 2. Lab Inverting Amp Values Input Voltage (V) Output Voltage (V) Gain 1.05 -15.3 -14.57 2.05 -28.1 -13.71

Page 5 3.06 -28.3 -9.25 Table 3. Pre-Lab Non-Inverting Amp Values Voltage Peak to Peak (V) Output Voltage (V) Gain 1 16 16 2 32 16 3 48 16 Table 4. Lab Non-Inverting Amp Values Voltage Peak to Peak (V) Output Voltage (V) Gain 1.13 13.9 12.3 2.09 26.7 12.78 3.14 27.5 8.76 Sample Calculations Inverting Amplifier Non-Inverting Amplifier - With voltage 𝐴 𝑣 = ? ??? ? 𝐼? 𝐴 𝑣 = ? ??? ? 𝐼? 𝐴 𝑣 = −15.3? 1.05? = − 14. 57 𝐴 𝑣 = 26.7? 2.09? = 12. 78 - With resistance 𝐴 𝑣 =− 𝑅 𝑓 𝑅 1 𝐴 𝑣 = 1 + 𝑅 𝑓 𝑅 1 𝐴 𝑣 =− 27𝑘Ω 2.2𝑘Ω =− 12. 27 𝐴 𝑣 = 1 + 27𝑘Ω 2.2𝑘Ω = 13. 27

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Page 6 3.2 Inverting Amplifier Images Figure 1: Breadboard configuration of inverting Figure 2: Oscilloscope with Input Voltage of amplifier circuit. 1V Figure 3: Oscilloscope with input voltage of Figure 4: Oscilloscope with input voltage of 2V 3V

Page 7 3.3 Non-Inverting Amplifier Images Figure 5: Breadboard configuration of Figure 6: Oscilloscope with input voltage of non- inverting amplifier circuit. 1V Figure 7: Oscilloscope with input voltage of Figure 8: Oscilloscope with input voltage of 2V 3V

Page 8 4 Discussion The gain from the simulation (pre-lab) is not the same value as the hands-on experiment for several reasons. Firstly, the circuit built in the lab uses resistors that are not exactly the values used in the simulation. In the pre-lab the resistances used were R1 = 2 KΩ and Rf= 30 KΩ for both the inverting and non-inverting amplifier. In the lab experiment the resistances used were R1=2.2kΩ and Rf= 27KΩ. It is above or below by a few decimals due to the equipment available for use in the lab. This discrepancy may be the cause for a larger discrepancy between the values sampled from the pre-lab and the lab experiment. The solution to this problem would be to find resistors that have a resistance closer to or exactly the ones used in the pre- lab simulation. Secondly, the voltage gain obtained from the pre lab gave accurate readings for each of the three trials. In the lab experiment on the other hand, the voltage gain in the third trial was not accurately calculated due to the equipment in the lab not having the capacity to increase the voltage from 15V. This is because the Op-amp does not have enough power to amplify the output voltage to 45 without increasing the voltage input. The maximum output voltage that can be obtained using either the inverting or non-inverting amplifiers in the lab was around 30V. When the expected value was 45V, the oscilloscope displayed values just below 30V. This did not affect the results from trials 1 and 2, because the output voltage did not exceed 30V in either case. The solution to this problem would be to increase the input voltage, however it cannot go over 15V because anything higher has a possibility to burn out the Op-amp and damage lab equipment. The main advantages of inverting and non-inverting amplifiers are that they increase the strength of a weak input signal, amplifying the desired signal and minimizing noise. Amplifiers allow for the ability to adjust the gain in a more flexible manner than other circuit designs. It is also advantageous that inverting amplifiers can be used when the input and output voltage must be out of phase depending on the circumstances, whereas non-inverting amplifiers the voltages are in phase. The non-inverting amplifier is better because the input resistance does not need to equal the source resistance. For inverting amplifiers, they are set up in a way that the source resistance and input resistance are the same, limiting the gain of the circuit. Since for non-inverting amplifiers, the values of these resistors can be different, the input resistance can approach infinity without negatively affecting the output.

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Page 9 5 Conclusion To conclude, this laboratory experiment explored the two distinct types of amplifiers- inverting and non-inverting. Amplifiers play a fundamental role in the augmentation of voltage and the power of a signal. In particular, the operation amplifier, referred to as the Op-Amp, was the main point of our laboratory. While the Op-Amp can serve multiple purposes, its main function is the amplification of voltage. In the non-inverting configuration, the input signal is directly routed to the non-inverting terminal, resulting in positive gain and an output voltage that is in phase with the input voltage. Contrarily, the inverting amplifier produces a negative gain and the output voltage is out of phase with the input voltage. It was discovered that a non-inverting amplifier is typically more useful than inverting due to its ability that the input resistance does not need to be the same as the source resistance, allowing the input resistance to increase as high as needed. It can be seen that the values of Rf and Rs affect the values of the gain, and differ from the gain values calculated when using voltage. This discrepancy can be attributed to the components of the circuit having non-ideal characteristics that were not taken into account when doing the required calculations. Using the pre-lab software we were able to see an idealized circuit analysis and compare that to the circuit analysis done in the lab.

Page 10 6 References 1. Basic electronics. (n.d.). http://vlabs.iitkgp.ernet.in/be/exp17/index.html# 2. ELG3336Lab1. ELG3336: Electronics for Mechanical Engineers [PDF]. D2L/Brightspace. https://uottawa.brightspace.com/d2l/le/content/387320/viewContent/5462768/View

Page 11 7 Appendix

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